Artificial limb



LA VAUGHN L. MORTENSEN 2,336,881

ARTIFICIAL LIMB I Filed Sept. 12, 1942 4 Sheets-Sheet l i 1': I g 41% LA VAUGHN L. MORTENSEN I) f I ,1 W

Dec. 14, 1943. LA VAUGHN'L. MORTENSEN ARTIFICIAL LIMB Filed Sept. 12, 1942 4 Shets-$heet 2 amen/1,507.1 LA VA u GHN L. MoRTENseN Dec. 14, 1943. LA VAUGHN L. MORTENSEN ARTIFICIAL LIME 4 Sheets-Sheet 3 Filed Sept. 12, 1942 :1 I won kw LAVAUGHN LMORTENSEN 5 Y/Z/ I Was - 1943- LA VAUGHN L. MORTENSEN 2,336,381

ARTIFICIAL mus Filed Sept; 12, 1942 4 Sheets-Shet 4 Patented Dec. 14, 1943 ST g zsiasi This invention relates to artificial limbs, and more particularly to mechanism for Controlling the relative movement of the several parts constituting an artificial limb. This application is a continuation-in-part of my application, Serial No. 323,318, filed March 11, 1940.

Heretofore artificial limbs that have included a knee joint have been subject to buckling when the users weight was thrown on the joint while the upper and lower limb sections were not in proper alignment. This fault has been particularly apparent when descending an incline. Knee brakes have been used in artificial knee joints heretofore but these brakes have been rendered effective only by extending the line between the knee and the heel of the foot section, and as a result of such construction they failed to afford aid when aid was most urgently needed.

Furthermore, previous artificial limbs that included a foot section have been uncomfortable and unnatural in action because they fail to permit the foot section to turn and repose in a natural manner. Heretofore in turning it has been necessary for the user to efiect a slight twist or pivot from the hip and no means was provided to permit the foot section to turn or twist with respect to the lower limb section as is natural in a normal walking motion. In like manner previous artificial limbs that included a foot section have been uncomfortable and conspicuous in a position of repose as when the user is in a sitting position. These disadvantages have been caused by previous failure to provide mechanism that permitted the foot section of the limb to assume an ormal floor-engaging position with respect to the lower limb member.

It is the primary object of this invention to provide control mechanism for artificial limbs including a knee joint and foot joint that will effectively prevent the knee joint from buckling. This mechanism is designed to provide aid in controlling the limb members, particularly in such situations where the aid is most urgently needed, as when descending an incline. To the end that this object may be attained, the invention provides a brake control mechanism and a resilient member coacting with and causing the brake control to be applied when weight is placed on the foot memebr.

Another object of the invention is to provide an artificial limb including a foot section connected to the lower limb member in such manner as to permit the foot section to twist or pivot in a normal manner with relation to the lower limb member. This object of the invention is attained by providing telescoping tubular members between the knee section and the foot section so that the foot section is free to actively swive1 sideways within a limited arc while walking or turning, and having resilient means for returning the rotary members to their normal position in which the toe of the foot will point approximately straight forward.

It is a further object of the invention to provide means for adjusting the length of an artificial limb including a lower limb member and this object of the invention is attained by providing bearing abutments in telescopic members constituting parts of a lower limb section between which bearing abutments spacing washers may be placed for the purpose of increasing or decreasing the length of the limb member within reasonable limits.

These and further objects and advantages of the invention will appear from a reading of the following description with reference to the accompanying drawings wherein like reference numerals indicate like parts and wherein:

Figure 1 is a vertical sectional view showing an artificial limb in which the invention is embodied;

Figure 2 is a cross sectional view of line 22 of Figure 1;

Figure 3 is an enlarged fragment of Figure 1 in the region of the ankle section;

Figure 4 is a fragmentary back view showing a slot in the lower tubular leg section;

Figure 5 is a Vertical sectional View similar to Figure 1 but showing the toe of the foot forced downwardly and the knee brake parts in braking position;

Figure 6 is a fragmentary cross sectional view of the limb showing the knee brake parts in flexed position;

Figure 7 is a cross sectional view on the same line as Figure 2 except that the tubular lower limb members are swiveled to the opposite extreme of their limited movement;

Figure 8 is a fragment of the upper end of the lower leg section viewing the rear part of the brake supporting framework;

Figure 9 is a cross sectional view of an artificial limb showing a modified form of knee brake wherein the limb sections are in flexed position;

Figure 10 is a cross sectional view similar to that in Figure 9 but showing the limb members in a straightened position assumed during Walking movement;

The artificial limb herein disclosed comprises a an upper limb member It, a lower limb member l2 and a foot member {4. The upper limb mem-i ber I and the lower limb member 12 are pivotally joined by means of a knee bolt |=3 while the lower limb member I2 anqjthe foot member M are pivotally joined by means of an ankle bolt l8.

- The. lower limb member I2 includes a tubular member to the upper end of which is attached a reenforcing and knee bolt-engaging brace 22. The tubular limb member 20 is received telescopically within a lower tubular member 24 that is located at and somewhat above the ankle portion of the limb, this lowertubularmember being in turn attached. to the ankle bolt is. Within the lowertubula member 2 3 is fixed an inwardly extending bearing abutment 26 and within the lower end of the upper member 20 is fixed an inwardly extending bearing abutment 28. The length of the lower limb may be'adjusted by spacing the bearing abutments 26 and 28 by means of one or more floating spacing washers 30 that are selected to provide the required exact length to the lower limb portion. In order to permit telescopic movement of the tubular member 20 and 24, the outer lower tubular member 24 has been provided with a slot 32 in which anextension of a clamping block 34 is adapted to extend. ;The clamping block 34 has 'anextension 36 which eXtt nd-s through the slot 32 and carriesfrom its extending portion a spring member 38 whichhas o ne I end thereof attached to the extension and the other end thereof attached to an 'rilltlrned ear 40 formed in the wall of the'inner tubular member 20. As a result of this construction, the foot member l4 'may swivel from side to side througha distance represented by the angular distance between the extension 36 and the plate 52 at a point indicated herein at 58.

The lower limb member 12 has attached to the upper part thereof a base plate 52 that extends upwardly into the upper limb member l8 and that has a passage therein for receiving the knee bolt It. To the base plate 52 is attached a brake shoe 54 adapted to engage a friction surface 55 formed either in the lower end of the upper limb section IE] or attached thereto. The friction surfaces of thebrake shoe 55 and the brake drum 56 are segmental in form and are so constructed as to engage and disengage each other at proper cycles during normal walking motion.

The braking shoe 54 is pivoted on the base A brake shoe connecting member 68 has one end thereof pivoted to the brake shoe e l as at 62.

' The opposite end of the brake shoe connecting anchor 40 of the opposite end of the spring 8.

Theswiveled position of the foot membe as it affects the telescopic lower limb members is best illustrated in Figure 7 of the drawings The spring 38 will return the telescopic sections to their normal position in which the footpeints substantially forward upon release of pressure on the foot member. The return movement of the foot is limited by a stop 42 and the same may be cushioned by cushioning member 44 carried on the face of the block 35 adjacent the stop member 42. 7 V

The lower limb member carries a thinrub ber stocking 45 that has a thicker padding 4%? for forming the side and back of th calf, the whole of 'whichgforms the shape of; the lower part of the'limb and ankle, and thisfstocking is fastened at its upper end to a suitable fastenin member .58. The upper limb member may includean-elastic member 51 that is adapted to return the lower limb when walking. Theelas:

- tic member 5| may engage an idle-roller Bacarried'by a knee brake hereinafter to be described;

member'fifl has a pivot 65 by means of which the same is connected to brake actuating mechanism. A brake actuating link 66 has its outer end 58 pivoted to the base plate 52 and its inner end H3 is pivotally connected to the outer end 64 of the brake shoe connecting plate Gil by means of an adjusting link such as a turnbuckle l2.

Pivotally connected substantially midway of the length of the link 66 is a brake actuating rod M, the pivot point being shown at "E8. The brake actuating rod It extends downwardly through the lower limb section and it is connected to an adjusting bolt 8fi extending upwardly from the toe section 82 of the foot member. An anchor 84 together with the pivoted link 83 guides the movement of the brake actuat ng rod M in order to maintain. the samein spaced relation with respect to the bearing abutments 26 and 28.

A spring 59 connects an upwardly extending portion ofthe brake shoe 55 to the base plate 52. A secondspring iii connects the brake shoe connecting plate BE! to the upwardly extending portion'of. the brake shoe 54. The spring 59 is substantially weaker than the spring 6! and, therefore, offers only slight resistance to the operation of the brake shoe 5 into frictional contact with the brake drum 56. The function of the spring 59 is to return the brake shoe to an inoperative position upon release of pressure that tends to force the toe portion of the foot member in a downward direction. The spring 523 permits the parts constituting the brake to move with respect to each other when the limb is in repose to permit the foot member to assume a natural fiat position on the floor. The spring {ii-permit a smooth resilient operation of the brake. By interposing the spring 6! between the brake shoe and its operating mechanism, it is always possible to secure a yielding braking contact between the friction surfaces. i

In the modified form of the invention there has been illustrated a different type of knee brake which, however, operates on the same principle as that illustrated and described withrespect to the foregoing form' of the invention. In the modified form of the invention the limb members have been more or less conventionally illustrated and it is to be understood, therefore,-that the rotatable and adjustable lower member heretofore described may be used with respect to the latter form of knee brake. s I

In Figures 9 and 10 there has been illustrated an upper limb member 88,al oweif limb member Siland a foot member 92,- the upper limb member 8 8;and the lower-limbmembertfi being pivotedwith respect to each other about a knee bolt 94% and the lower limb member 99 and the foot member 92 being pivoted with respect to each other by means of an ankle bolt 96.

In this embodiment of the invention the knee brake consists of a base member 93 which is attached to the lower limb member 96 in any suitable manner. The base plate 98 carries therein a pivoted segmental brake shoe IEO. Attached to the upper limb member is a brake drum element ldZ with which the segmental brake shoe Hit is adapted to engage for effectively braking any buckling action between the respective limb members 83 and 98.

The brake drum N32 is of general U-shaped form wherein the base of the U forms the friction surface for the brake shoe Hill. The ears or open ends of the U are each provided with means that are adapted to encircle the knee bolt in such manner that the tension of the knee bolt encircling member may be adjusted for the purpose of regulating the pendulum movement of the limb. In the present case this means has been illustrated as split rings Hi3 which have extending through their open ends adjusting bolts 5%. It can be readily seen that by adjusting the bolts ltd, the frictional grasp of the split rings 6% on the knee bolt M can be adjusted to any desired degree.

The base plate 323 supports the brake shoe ltd through the provision of an angle plate Hi5 pivoted to the plate 98 at its outer point Hi3. To the depending portion of the angle plate Hi6 is attached the upper end of a brake actuating rod 5 it, the attachment between the rod 5 it and the angle plate W5 being effected through a rotatable member 5 !2 through which the actuating rod I it passes.

The actuating rod lid is composed of a link adjusting member lit, a spring HE and a lower rod portion H8, these members being connected in series so that in efiect they operate as a single actuating member. The lower end of the rod I i8 is pivoted at E to a bolt I22 located in the toe section of the foot member.

It is to be noted particularly that the angle plate ltd is held in a retracted position by means of a spring 522, one end E26 of which is attached to the angle plate ltS and the other end I28 of which is attached to the base plate 98. The spring i it: is of considerably greater strength than the spring l2t so that the spring I oiiers relatively small resistance in the application of the brake. The spring l2 l has been designed primarily to return the angle plate Hi6 and the brake shoe 89 to the inoperative position upon release of braking pressure on the foot member. In this form of the invention the spring we permits a natural position of the foot member when the limb is in repose.

A resilient block I39 may be carried by the base plate 98 at the point where the brake drum it?! abuts the base plate 98 for the purpose of cushioning the abutting movement. A roller I32 maybe carried at the upper outer corner of the base plate 95 for the purpose of accommodating an elastic member such as 5i in Figure 1.

In both forms of the invention thus far described, there has been illustrated a brake actuating mechanism that is attached at its lower end to the toe section of the foot member. It is to be understood, of course, that these mechanisms may perform their intended function even the knee bolt.

trated an arrangement of the actuating rod wherein the ultimate brake operating impulse is obtained from the heel section of the foot member. The lower limb member its is pivotally connected with the foot member 13% by means of an angle'bolt use. The ankle bolt in this case is illustrated as being composed of a pair of uprights ltd to the top of which is attached a cross member It? having upstanding ears ltd adapted to receive therebetween a lever M3 and to which the lever its is pivoted at substantially its center M8. The brake operating rod Q55 has its lower end 952 pivoted to one end of the lever its and the opposite ends of the lever its is pivoted to a downwardly extending rod Mb having its lower end attached to the heel section I58 of a foot member. A smoother operation and a resilient action can be obtained by interposing a resilient member such as a relatively soft rubber let between the rod H55 and the heel E58. It will be observed that the ultimate braking force resulting from the construction shown in Figure 14 is exactly like that shown with respect to the first two embodiments of the invention; that is to say, when the toe section of the foot member is depressed, the actuating rcd will be drawn downwardly and the braking surfaces will be brought into braking contact with each other.

In the construction of artificial limbs it frequently is found that the knee bolt passages somewhat larger than necessary either as sult of the original construction or from subsequent wear. In order to eliminate noise that may flow from a knee joint assembly wherein the knee bolt and the passages through which it extends fail to fit with sufficient snugness, there is provided a laterally extending block l'l't that is carried by the base 98 in a location adjacent the knee bolt and substantially parallel to the axis thereof. The block lid has a passage extending therethrough and into the passage is threaded a set screw illl that is adapted to engage the knee bolt with its inner end whereby the knee bolt passages may be drawn into tight Contact with In this manner all cause for noise arising from faulty constructions and the like can be eliminated.

In the heretofore described forms of the invention there has been shown a rality or" sp; devices for the purpose of obtanlng a smooth operation of the several parts and for returning respective parts of the limb to a normal position. It is, however, obvious that these spring devices may be resilient devices of any nature effective to accomplish their intended purposes. Consequently the devices shown in Figures 13 and 16 have been provided to suggest such substitutions. In Figure 13, which is a cross sectional view similar to that shown in Figures 2 and '7, the spring element has been eliminated a segment of rubber 6E2 been substituted. Herein the segment of rubber 582 is positioned between a stop iE 'l extending inwardly from the inner tubular lower limb section and the wardly extending abutment ltd is positiened between the inner end its of a hook il'fi and the outer end of a yoke E? T re resilient device shown Figure 15 may be substituted, for example, for the spring l- Figures 9 and iii of the drawings.

The operation of the knee brake in both em} bodiments of the invention should be clear from the foregoing but in order that it may be even morer'eadily understood, the operation thereof will be summarized here. 7

With reference to that form of the invention shown best in Figures 1, and 6, 'it is to'be noted that in Figure 6 when the upper and lower limb members I!) and it are flexed withrespect to each other and with no pressure on the foot tending to press the toe section downward, the segmentalbrake drumis out'of' contact with the segmental brake shoe surface 56 and consequently no braking action can result. However, when the limb sections Iii and I2 are brought into alignment 'as shown in Figure 1, the braking surfaces of the knee brake are in face to face relation but yet the faces are not in braking contact. When the limb is swung forward as in the action of walking and the heel section strikes the surface'thus tending to force the toe section downwardly as more particularly shownin Figure 5 of the drawings, the brake actuating rod i i will bedrawn with the result that the brake drum surface will be engaged by the brake shoe against the tension of the springs 53 and ti.

' It is to be noted that this action takes place at the time when the tendency for the knee to buckle is the greatest, that is to say, when the users weight is substantially all on the artificial limb and the limb is in a somewhat forward position. As the stride is completed and the toe section moves upwardly with respect to the user is in a seated position and as a consequence,

of the fact that the brake shoe, because of its segmental form, may move angularly out of the range of the brake drum, the foot member is permitted to repose in a natural position durwardly with. the result that the tendency to.

buckle. when the weight of the user is first. transferred to the artificial limb'will be effectively overcome. I H

The action of the "foot member swivel growing out of the arrangement or" the telescopic lower limb sections as best illustrated in Figures 2 and 3 has already been described and further descriptionof its operation is deemed unnecessary. r 7

It is important to note that the invention results in a knee brake that has substantially all of its elements located'belo'w the knee bolt, thereby making the benefits thereof available to persons having long stumps. This among the other advantages renders the invention universally useaesaser I claim:

1. An artificiallimb comprising an upper limb member and a lower limb member, a knee joint pivotally connecting said members, a brake drum carried by one of said limb members, a brake shoe carried by the other of said limb members and being adapted to coact with said brake drum to brake the pivotal movement of the knee joint, a foot member including toe and heel sections, a pivot connecting said foot member to the lower end of said lower limb member, a resilient brake actuating member connected with said brake shoe and extending downwardly in said limb member, and means connecting said actuating member and said foot member whereby the downward movement of the toe section of said foot member moves said actuating member to apply said brake.

2. An artificial limb comprising an upper limb member and a lower limb member, a knee joint pivotally connecting said members, a brake drum carried by one of said limb members, a brake shoe carried by the other of said limb members and being adapted to coact with said brake drum to brake the pivotal movement of the knee joint, a foot member including toe and heel sections, a pivot connecting said foot member to the lower end of said lower limb member, a brake adjusting member connected with said brake shoe and extending. downwardly in said limb member, a resilient member connected in series with said adjusting member, and means connecting said adjusting member and said resilient member with said foot member whereby the downward movement of the toe section of said foot member moves said adjusting member and said resilient member to apply said brake with a resilient pressure.

3. An artificial limb comprising an upper limb member and a lower limb member, a knee joint pivotally connecting said members, a brake drum carried by one of said limb members, a brake shoe carried by the other of said limb members and being adapted to coact with said brake drum to brake the pivotal movement of the knee joint, a foot member including'toe and heel sections, a pivot connecting said foot member to the lower end of said lower limb member, a brake actuating rod including a resilient section connected with said brake shoe and extending downwardly in said lower limb member, means connecting said actuating rod to said foot member at a point between its pivot and the toe section whereby the downward movement of the toe section of said foot member moves said actuating rod to apply said brake with a yielding pressure.

4 An artificial limb comprising an upper limb member and a lower limb member, a knee joint pivotally connecting said members, a brake drum carried by one of said limb members, a brakeshoe carried by the other of said limb members and being adapted to coact with said brake drum to brake the pivotal movement of the knee joint, a foot member pivotally connected to the lower end of said lower limb member, brake operating 5. An, artificial limb comprising an upper limb member, a lower limb member and a pivoted foot member, a? knee jointpivotally connecting said upperandi lower limb members, a segmental brake drum carried by one of said limb members,

a segmental brake shoe carried by the other of said limb members, a positive brake actuating member connecting said brake shoe and said foot member, one of said brake elements being associated with the other to move arcuately out of engagement with the other brake element upon predetermined flexing movement of the limb members at said knee joint.

6. An artificial limb comprising upper and lower members pivotally connected together simulating a knee joint, a segmental brake drum element and a segmental brake shoe element carried by said members, said elements occupying a coactive position when said members are extended and an arcuately displaced inoperative position when said members are flexed, yielding means tending to hold said elements from engagement, at least when said members are extended, a foot member pivotally connected with said lower member, and a resilient member for resiliently actuating said brake elements in opposition to said yieldable means upon pivoting of said foot mom ber.

7. In an artificial leg, the combination with a thigh, foreleg, and foot simulating members connected by knee and ankle simulating joints, of an inclined descending brake, comprising coactive brake elements incorporated in said knee joint to resist fiexure of said foreleg, resilient means tending to release said brake elements, and a link and a resilient member connected with said foot member for resiliently applying said brake elements when said foot member pivots in response to pressure on its heel incidental to use of the artificial leg in descending an incline.

8. An artificial limb comprising an upper and lower part, a knee joint having a brake drum element fastened to the upper part of the limb coacting with a movable friction element carried from the lower part of the limb, a pivoted foot piece, a spring to normally prevent the friction element from dragging on the drum element, a lever pivotally connected to the friction element, a pull rod and a spring interconnecting the pivotal foot piece and said lever whereby pivotal downward movement of the front part of the foot piece is effective to resiliently force the friction element against the brake drum element causing the knee to be more resistant to fiexure.

An artificial leg comprising telescoping members simulating the foreleg and having limited normal circumferential movement with respect to each other, and resilient means connected between said members and tending to return the members to their original positions with respect to each other.

ii). An artificial leg comprising telescoping members having limited normal circumferential movement with respect to each other, one of the telescoping members at leastpartiall forming th shape of an ankle and the other member at least partially forming the shape of the shin, resilient means connected between said members and tending to return the members to their original positions with respect to each other, and yielding means limiting the said circumferential movement of one member with respect to the other under the action of the resilient means.

11. An artificial limb comprising an upper part, a knee joint, a lower part having two tubul r parts one of which is telescoped within the other, a pivoted foot piece, a bearing surface on one of the tubular parts adapted to engage the bearing surface of the other tubular part to form an active swivel, a resilient connection between the two tubular parts whose function is to return said parts to their normal position of alignment after having been swiveled from said normal position.

12. An artificial limb comprising an upper part, a knee joint, a lower part having two tubular parts one of which is telescoped within the other, a bearing surface on one of the tubular parts adapted to engage the bearing surface of the other tubular part to form an active swivel, a resilient connection between the two tubular parts whose function is to return said tubular parts to their normal position of alignment after having been swiveled from said normal position, a pivoted foot piece, a knee brake, a resilient connection between the foot piece and the knee brake whereby the pivotal downward movement of the front part of th foot piece applies the knee brake so that the knee is more resistant to fiexure.

13. An artificial limb comprising an upper part, a knee joint, a lower part having two tubular parts one of which is telescoped within the other, a bearing surface on one of the tubular parts adapted to engage the bearing surface of the other tubular part to form an active swivel, a resilient connection between the two tubular parts whose function is to return said tubular parts to their normal position of alignment after having been swiveled from said normal position, a pivoted foot piece, a knee brake, a resilient connection between'the foot piece and the knee brake whereby the pivotal downward movement of the front part of the foot piece applies the knee brake so that the knee is more resistant to flexure, a rubber stocking which is much thicker in the calf part for shaping and covering the lower part of the limb. V

14. In an artificial limb comprising an upper limb member and a lower limb member, a knee bolt pivotally connecting said members to form a knee joint, a segmental U-shaped friction brake element carried by said upper limb member, a pair of split rings at each side of said friction element disposed in knee bolt encircling relation,

and an adjusting screw interconnecting the free ends of each of said rings for contracting said rings about said knee bolt whereby the pendulum action of said oint may be adjusted.

15. The combination with an artificial limb having upper and lower members pivotally connected to simulate a knee joint and a foot member pivotally connected with said lower member to simulate an ankle joint, of a knee brake to retard the pivotal movement of said knee joint when the artificial limb is employed in descending an incline, and. a resilient element connecting the knee brake with the foot member for resiliently actuating said knee brake upon pivotal movement of said foot member in response to pressure on its heel.

16. An artificial limb comprising an upper limb member and a lower limb member, a knee joint pivotally connecting said members, a brake drum carried by one of said limb members, a movable friction element carried by the other of said limb members and being adapted to coact with said brake drum to brake the pivotal movement of the knee joint, a foot member pivotally connected to the lower end of said lower limb member, a resilient element to normally prevent the movable friction element from dragging on the brake drum, a brake operating rod connecting said movable friction element with the foot member, and a spring member interposed between said movable friction element and said operating rod for yieldingly urgingthe movable friction element into engagement with the brake drum upon pivotal movement of the foot member in response to pressure on its heel. i L

1'7. An artificial limb having uppercand lower members pivotally connected together to simulate a knee joint, a foot member pivotally connected with said lower member to simulate an ankle joint, a knee control device having coactive members,0ne' of said co-active members being attached to said upper limb member and the other of said co-a'ctivemembers being attached to said lower limb member, a resilient knee control actuating member, means connecting said resilient member to said knee control device and to said foot member whereby" pivotal movement of the foot member causes said resilient'member to resiliently actuate said knee control so that said knee joint is resistant to flexure 18. An artificial limb having upper and lower members pivotally connected together to simulate a knee joint, a foot member pivotally connected with said lower member to simulate an ankle joint, a knee brake, a resilient member interconnecting said knee brake and said foot member, said resilient member constituting a resilient actuator for said knee brake whereby said brake is resiliently engaged in braking position when weight is placed on said foot member.

19. An artificial limb 'having upper and lower members pivotally connectedtogether to simulate a knee joint, a foot member pivotally connected with said lower member to simulate an ankle joint, a segmental brake drum associated with one ofsaidlimb members, a segmental brake shoe being associated with the other of said limb members, a resilient member interconnecting said segmental brake drum and brake shoe to cause a braking action that is resistant to knee flexure when weight is placed on the foot member.

20.. An artificial limb having upper and lower members ,pivotallyconnected together to simulate a knee joint, a foot member pivotally connected upper and lower limb members are angularly disposed as when in a seated position.

21. An artificial limb having upper and lower members pivotally connected together to simulate a knee joint; a foot member pivotally connected with said lower member to simulate an ankle jointfasegmental brake drum element and a segmental brake shoe element carried by said members, said segmental braking elements occupying a co-active braking position when said limb members are extended in an 'arcuately displaced non-braking position upon predetermined angular position of the limb members at said knee joint, a yielclable member tending to hold said braking elements from braking engagement, a resilient brake actuatin member interconnectingsaid segmental brake elements and said foot member, said resilient member being efiective to resiliently actuate said brake elements into braking contact upon pivotal movement of said foot member to cause said knee joint to resist fiexure, said arcuately displaced position of said segmental elements permitting the foot member to assume a natur'al position against opposition of said yieldable member when the upper and lower limb members are angularly related as in a seating position.

' LA VAUGHN L. MoRTENsEN. 

